Peculiarities of zebra structures within the microwave range

Studying mechanisms of radiation of zebra-type spectral structures attracts great attention because frequencies of stripes and characteristics of their frequency drifts contain information on plasma parameters in coronal parts of flare loops. This paper is concerned with observations of microwave zebra structures in events with dynamic spectra recorded by National Astronomical Observatory of China (NAOC) spectropolarimeters and the emission band close to observation frequencies of the Siberian Solar Radio Telescope (SSRT). The localization of emission sources in the flare area allowed us to estimate plasma parameters in the generation region from X-ray data. The interpretation of zebra structure observations in terms of existing mechanisms is discussed. The conclusion has been justified that the preferred zebra-structure generation mechanism in the microwave range is the plasma oscillation conversion into electromagnetic emission on double plasma resonance surfaces distributed across the magnetic field of a flare loop.